Automation has not been explosive in the last 15 years, I'm not sure why you think this. Productivity growth (the measure of increasing automation) has been the lowest its been in decades, see here: https://www.zerohedge.com/sites/default/files/images/user330...
As for whether we need 30 million engineers, thats entirely up to what we want to be as a society. If you don't think we can come up with engineering work for 30 million people I beg to differ.
Not a good measure, because so many are reduced to service industries. Factory automation has been a headlong rush to automation for decades.
We're down 5M factory jobs since 2000, to something like 13M. And the rest are slated to go as automation becomes cheaper. When factories 'come back' from overseas, its only because now automation is even cheaper than foreign labor.
